Gas concentrator with removable cartridge adsorbent beds

ABSTRACT

A portable oxygen concentrator designed for medical use where the sieve beds, adsorbers, are designed to be replaced by a patient. The concentrator is designed so that the beds are at least partially exposed to the outside of the system and can be easily released by a simple user-friendly mechanism. Replacement beds may be installed easily by patients, and all gas seals will function properly after installation.

RELATED APPLICATIONS

This application is a Continuation of U.S. application Ser. No.15/608,788 filed May 30, 2017 which is a Continuation-in-Part of U.S.application Ser. No. 15/427,948, filed Feb. 8, 2017 which in turn is aContinuation of U.S. application Ser. No. 13/066,716, filed Apr. 22,2011

FEDERALLY SPONSORED RESEARCH

Not Applicable

SEQUENCE LISTING

Not Applicable

BACKGROUND OF THE INVENTION

The invention generally relates to gas concentrators, and moreparticularly relates to medical oxygen concentrators used by patients inthe home care setting where cost and frequency of maintenance performedby a technician should be minimized.

The application of oxygen concentrators for therapeutic use is known,and many variants of such devices exist. A particularly useful class ofoxygen concentrators is designed to be portable, allowing users to moveabout and to travel for extended periods of time without the need tocarry a supply of stored oxygen or to have any maintenance performed ontheir equipment. These portable oxygen concentrators are typically inthe range of 2 to 20 lbs and produce from 0.3 to 5.0 LPM of oxygen. Mostof these portable concentrators are based on Pressure Swing Adsorption(PSA), Vacuum Pressure Swing Adsorption (VPSA), or Vacuum SwingAdsorption (VSA) designs which feed compressed air to selectiveadsorption beds. In a typical oxygen concentrator, the beds utilize azeolite adsorbent to selectively adsorb nitrogen, resulting inpressurized, oxygen-rich product gas.

The main elements in a typical portable therapeutic oxygen concentratorare shown in FIG. 1. Air is draw in, and typically filtered, at airinlet 1 before being pressurized by compressor 2 to a pressure of 1.2 to2.5 atmospheres. The pressurized air is directed by a valve arrangementthrough adsorbent beds 3. An exemplary adsorbent bed implementation,used in a concentrator design developed by the inventors, is two columnsfilled with a lithium exchanged zeolite adsorbent in the ratio of about1 gram of adsorbent per 1-10 ml of oxygen produced per minute. Thepressurized air is directed through these adsorber vessels or columns ina series of steps which constitute a gas separation cycle, often a PSAcycle or some variation including vacuum instead of, or in conjunctionwith, compression yielding overall compression ratios of about 1.5:1 to4.0:1. Although many different arrangements of adsorber vessels and gasseparation cycles are possible, the result is that nitrogen is removedby the adsorbent material, and the resulting oxygen rich gas is routedto a product gas storage device at 4. Some of the oxygen product gas canbe routed back through the bed to flush out (purge) the adsorbednitrogen to an exhaust 6. Generally multiple adsorbent beds, or columnsin the exemplary device, are used so at least one bed may be used tomake product while at least one other bed is being purged, ensuring acontinuous flow of product gas. The purged gas is exhausted from theconcentrator at the exhaust 6.

Such gas separation systems are known in the art, and it is appreciatedthat the gas flow control through the compressor and the adsorbent bedsis complex and requires precise timing and control of parameters such aspressure, flow rate, and temperature to attain the desired oxygenconcentration of 80% to 95% purity in the product gas stream.Accordingly, most modern concentrators also have a programmablecontroller 5, typically a microprocessor, to monitor and control thevarious operating parameters of the gas separation cycle. In particular,the controller controls the timing and operation of the various valvesused to cycle the beds through feed, purge, and pressure equalizationsteps which make up the gas separation cycle. Also present in mostportable concentrators is a conserver 7 which acts to ensure that oxygenrich gas is only delivered to a patient during inhalation. Thus, lessproduct gas is delivered than by means of a continuous flow arrangement,thereby allowing for smaller, lighter concentrator designs. A pulse ofoxygen rich air, called a bolus, is delivered in response to a detectedbreath via the conserver. Using a conserver in conjunction with a gasconcentrator may reduce the amount of oxygen required to maintainpatient oxygen saturation by a factor of about 2:1 to 9:1. A typicalconcentrator will also contain a user/data interface 8 includingelements such as an LCD display, alarm LEDs, audible buzzers, wirelessdata interface devices, data ports, and control buttons. In addition tothe above subsystems, most portable oxygen concentrators contain atleast one rechargeable battery and a charging system to power theconcentrator while away from an AC or DC power source. These batterysystems are typically composed of lithium ion cells The battery systemscan power the concentrator from 2-12 hours depending on the amount ofoxygen required by the patient, device efficiency, and the capacity ofthe battery pack which may range from about 40 Watt-hours to 250Watt-hours on systems with multiple battery packs. Additionally theconcentrator charging system may boost battery or input voltages toefficiently run system components or charge batteries from a lowervoltage power source like a automotive DC power source.

To be practical and usable by a individual needing therapeutic oxygen,portable oxygen concentrators should be less than about 2100 cubicinches and preferably less than 600 cubic inches in total volume, lessthan about 20 pounds and preferably less than 5 pounds in weight, andproduce less than about 45 decibels of audible noise, while retainingthe capacity to produce a flow of product gas adequate to provide for apatient's oxygen needs, usually a flow rate prescribed by a medicalpractitioner in about the range of 1 LPM to 6 LPM or more particularly,to maintain a blood oxygen saturation level of 90% or greater. Further,a portable medical oxygen concentrator must work under variedenvironmental conditions such as 0° C. to 40° C. and 0%-95% relativehumidity without costly or frequent service or maintenance requirements.Although fixed site PSA based concentrators have been available for manyyears, such fixed site units may weigh 30-50 pounds or more, be severalcubic feet in volume, and produce sound levels greater than 45 dBA. Thusportable concentrators involve a significant amount of miniaturization,leading to smaller, more complex designs compared to stationary units.System size, weight, and complexity may lead to fewer mitigative optionsor design choices against contamination and other wear and tear effectsthat can lead to an unacceptably short maintenance interval when theportable concentrators may be required to supply oxygen around theclock.

One particular challenge of portable concentrator design is that theadsorbent beds must by necessity be small, yet capable of producing anadequate quantity of product gas. A portable oxygen concentrator mightrequire oxygen production of greater than 3 ml of oxygen per minute pergram of adsorbent in order to achieve an acceptable size of less than600 cubic inches. Since the adsorbent beds are optimized for O₂production per gram of adsorbent, any significant decrease in capacityof the beds over time can result in decreased product purity as therequired O₂ production per gram of active adsorbent exceeds the limitsof the adsorbent and PSA cycle operating parameters. One contributingfactor that can lead to a decrease in bed capacity is the adsorption ofimpurities that do not completely desorb during normal processoperation, leading to the accumulation and retention of impurities inthe beds and therefore less active adsorbent than originally intended inthe design. An example of such an impurity that reduces the adsorptioncapacity of many zeolites used in air separation is water. Somestationary concentrators utilize some means of removing water from thecompressed gas before feeding the adsorbent beds, but most rely on anexcess quantity of adsorbent to allow for contamination over time.Portable concentrators, by the nature of their application, are morelikely to be exposed to a wide range of operating conditions includinghigh humidity environments and/or rapid temperature changes that couldresult in the need for more frequent zeolite replacement. If water ispresent, either in the form of liquid (condensed out of the compressedair feedstream) or vapor, and enters the molecular sieve beds, the bedswill irreversibly adsorb at least some of this water during eachadsorption cycle. The energy of adsorption of water on lithium exchangedzeolites used in air separation is very high and not all water adsorbedduring the adsorption steps in the process is desorbed duringevacuation/purge of the beds under typical PSA cycle operatingparameters. Therefore, complete removal of adsorbed water from zeolitebeds usually entails applying some sort of energy to the beds, such asthermal, infrared, or microwave, and purging with a dry gas or applyinga vacuum to the beds during the regeneration process. These regenerationprocesses are impractical in a portable concentrator due to hightemperature or high power requirements. As a result, the accumulation ofadsorbed water over time results in a reduction in capacity of the beds,as fewer sites are available for nitrogen binding. Fewer binding sitesin the adsorbent bed can result in a decrease in product purity overtime as nitrogen passes through the sieve beds and dilutes the oxygenproduct gas, and shortens the service life or service interval of theconcentrator. Many zeolites used in air separation, and in particularadvanced adsorbents, particularly the high lithium containing low silicaX type zeolite (LiLSX) used in portable concentrators, are hydrophilicin their activated state due to the interaction of the strong dipolemoment of water molecules with the electric fields present in the LiLSXcages and can therefore be prone to this problem. In the effort to makemore compact and efficient concentrators, PSA cycle frequencies canincrease to rates approaching 10 cycles per minute and adsorbentproductivity increases accordingly with advances in process andadsorbent technology to productivities exceeding 10.0 ml of oxygen perminute per gram of adsorbent. The corresponding decrease in adsorbentinventory exacerbates the problem as the amount of gas processed perunit of adsorbent increases proportionally, (the bed size factordecreases) and the presence of impurities in the process gas candeactivate the adsorbents at a much faster rate than with conventionalPSA processes, as described in U.S. Pat. Nos. 7,037,358 and 7,160,367,which are incorporated by reference herein.

It is therefore necessary to design portable oxygen concentrators suchthat zeolite contamination can be prevented or handled in a manner thatavoids costly or frequent maintenance by a field technician or equipmentprovider. While the inventors have previously disclosed a system thatachieves long sieve bed life by removing water prior to the feed gascontacting the zeolite in U.S. Pat. Nos. 7,780,768 and 8,580,015, whoseteachings are incorporated by reference, this approach adds size andcost to the system to achieve its resistance to zeolite contamination.It is therefore desirable to design a portable oxygen concentrator thatminimizes size and weight as a function of oxygen output with commonlyavailable commercial adsorbents such as Z12-49 or OP-76 manufactured byZeochem, Nitroxy SXSDM, Nitroxy Revolution or Nitroxy NeXTmanufacturedby Arkema, or Oxysiv MDX manufactured by UOP. While eliminating waterremoval components such as membrane air dryers or pretreatment layerssuch as activated alumina or an NaX type zeolite will reduce the sizeand weight of the sieve beds it will also reduce the service life of thesieve beds to an unacceptable level. Oxygen equipment used for Long TermOxygen Therapy (LTOT) is optimally deployed for 3-5 years without anyservice requirements. Any service requirement within that time intervalsimply adds to the overall cost of the equipment, which substantiallyreverses any cost benefit gained by removing a membrane air dryer orpretreatment layer. Further, allowing sieve bed contamination withoutprevention or service may lead to providing 82-87% purity oxygen insteadof 87-95% pure oxygen to the patient. At this time, portable oxygenconcentrator adoption will require smaller, lighter devices that do notrequire field service by a technician or equipment provider, but alsominimize size and cost of the equipment.

A typical adsorbent bed or adsorber is constructed of a column with aninlet port and an outlet port arranged at opposite ends. The inlet portis used for admitting pressurized feed gas from the compressor as wellas exhausting the waste gas out of the system in the countercurrent(opposite to the direction of flow of the feed gas) direction. Theoutlet port allows product gas to flow to the accumulator or outputwhere it can be delivered to the patient. The outlet port also admitsproduct gas back into the exhausted sieve bed in the countercurrentdirection to purge the column of remaining waste gas prior tointroducing additional feed gas. Inlet and outlet ports must create asealed connection to allow pressurized feed gas and product gas to passinto and out of the columns without wasteful leaks that would upset thebalance of the system or let oxygen rich product gas escape from thesystem. The inlet and outlet port connections are typically composed ofbarb fittings, quick connect fittings, tapered pipe thread fittings, orintegrated manifold connections such as adhesives, face seals, gaskets,o-rings or straight threads. The adsorbers would typically be connectedto the valve manifold of the concentrator through tubing or a directmanifold connection. Either prior art construction method resulted in arobust pneumatic connection that was only meant to be disconnected by atrained service technician who could access the internal components ofthe concentrator and disconnect or disassemble the inlet and outletconnections. Some columns, such as those that are adhesive bonded to anintegrated manifold, may not be removable at all in a field serviceenvironment and must be replaced in combination with other systemcomponents to achieve zeolite replacement.

BRIEF SUMMARY OF THE INVENTION

The invention is a portable oxygen concentrator platform, including aPSA/VPSA/VSA core section capable of mating with user replaceableadsorbers. The core section includes all of the concentratorinstrumentation, mechanics, and pneumatics other than the adsorbers andincludes a housing; a controller; a user interface; at least onecompressor, air control valve, and air filter, comprising a PSA/VPSA/VSAoxygen system when mated with user replaceable adsorbers; and a patientdelivery apparatus. The core also includes at least one adsorberreceptacle that is capable of mating to a user replaceable adsorber. Thereceptacle includes at least two pressure sealed gas connections toinlet and outlet ports of the core section, at least two easilydisconnectable pressure sealed gas connectors for mating to an inlet andoutlet port on a user replaceable adsorber, and a user operable adsorberretention mechanism. Mating a user replaceable adsorber with theadsorber receptacle forms a complete portable oxygen concentrator. Theinvention is applicable to the portable medical concentrator field wherethe concentrator preferably weighs less than 10 pounds, produces lessthan 45 dba acoustic noise when operating, and has an output gas flow of5 lpm or less and has rechargeable battery capable of running theconcentrator for greater than 2 hours. In a preferred embodiment, theconcentrator weighs less than about 5 pounds.

The invention also may be a combination of the platform section and atleast one user replaceable adsorber, forming a complete portableconcentrator. The user replaceable adsorber capable of mating withcompatible portable oxygen concentrator platform includes at least oneselective adsorbent, disconnectable pressure sealed gas connectors formating to the platform receptacle inlet and outlet connectors, andmating retention mechanism to the platform adsorber receptacle retentionmechanism.

In certain embodiments, the battery mounts to the instrumentationsection and prevents removal of the adsorbers while the battery isattached, and there may be a removable case that encloses the platform,user replaceable adsorber beds and battery when all three are mountedtogether.

In other embodiments the inlet and outlet ports may include one or moreradial seals, and the adsorber and receptacle ports insert beyond theradial seal by at least 1-5 mm. The leak rate of the seals is preferablyless than about 10 SCCM over the device operating pressure or vacuumlevel of the adsorber which may be from 0.2 atmospheres to 3.0atmospheres. In certain embodiments the adsorber ports are coaxial withthe receptacle ports. In other embodiments pneumatic gas seals mayinclude one or more face seals where portions of the adsorbent bedstructures are common to more than one adsorber.

In some embodiments either the platform or adsorber retention mechanismcomprises a sliding spring loaded plunger and the corresponding matingretention mechanism includes a slot which mates with the plunger. Thespring loaded plunger snaps into the slot when the adsorber is mated tothe platform thereby retaining the adsorber and actuation of the plungerreleases the adsorber. The retention force of the release mechanism ispreferably less than about three pounds, and the plunger may be fingeractuated to release the adsorber.

In other embodiments, either the platform or adsorber retentionmechanism includes a screw operated tab and the corresponding matingretention mechanism includes a slot which mates with the tab. The tab isrotated into the slot when the adsorber is mated to the platform therebyretaining the adsorber and reverse rotation of the tab releases theadsorber.

In other embodiments, the platform retention mechanism includes a pushbutton actuated spring loaded plunger and the adsorber retention matinghardware includes a slot which mates with the plunger. The spring loadedplunger snaps into the slot when the adsorber is mated to the platformthereby retaining the adsorber and push button actuation of the plungerreleases the adsorber. The adsorber is preferably released with lessthan about 25 Newtons of force applied to the push button, and theremovable adsorber mates to the instrument section in an axisperpendicular to the flow of gas through the column.

In some embodiments, the adsorber receptacle gas connections areconnected to the air control valves by compliant pressure members. In aparticular version, the adsorber receptacle gas connectors are directlyconnected to the compliant members, and when connected to the compliantmembers, are held in place by a housing mounting element structurallyindependent from the receptacle gas connector. In an alternativeembodiment at least one of the gas connections could be directly to amanifold.

In other embodiments, the platform retention mechanism includes athreaded adsorber and threaded adsorber receptacle. The inlet and outletports may be coaxial and located on one end of the adsorber. Theadsorber or the adsorber receptacle have radial seals that enable thesealing of the gas connection in any rotational orientation around thecenter axis of the adsorber.

In certain embodiments, the adosrber is retained to the receptacle by atwist to lock mechanism. The twist lock may be engaged by less thanabout 180 degrees of rotation, and the inlet and outlet ports may becoaxial and located on one end of the adsorber.

In other embodiments, the platform retention mechanism includes a hingedcover. The hinged cover snaps into place when the adsorber is mated tothe platform thereby retaining the adsorber, and opening the coverreleases the adsorber. The hinged cover may preferably be disengagedwith less than about 25 Newtons of force and can be operated by afinger.

In other embodiments, one of the inlet or outlet ports is rigidlymounted to the receptacle by any of a twist to lock or threadedengagement and at least one of the inlet of outlet port connections ismade by attaching a flexible tube to the port.

In one or more embodiments, a portable oxygen concentrator, may beprovided including a platform, including a housing, a controller, a userinterface, at least one compressor, air control valve, and air filter,an oxygen delivery apparatus, at least one adsorber receptacle includingat least one gas connector port and at least one adsorber retentionelement; and at least two separable user replaceable adsorbers includingan adsorber having a top end and a bottom end, the adsorber configuredto contain a nitrogen selective adsorbent material, wherein a flow axisof gas through the column may be between the top and bottom ends, atleast one retention element on the adsorber configured to mate directlywith an adsorber receptacle retention element and, a first and a seconddisconnectable pressure sealed gas connector disposed on the top andbottom ends of the column respectively, wherein the gas connectors maybe in fluid communication with the adsorbent and may extend at least oneof in parallel or perpendicularly to the flow axis in substantially thesame direction and the central axes of the gas connectors may besubstantially parallel to each other; wherein the adsorbers may beconfigured to mate with the platform to form a complete oxygenconcentrator, the retention mechanism may be accessible on the exteriorof the platform, and at least one of the adsorber or the adsorberreceptacle retention mechanisms may be hand operable; and at least twoadsorbers may be attached together and have a common retentionmechanism; wherein the concentrator weighs less than 10 pounds, producesless than 45 decibels acoustic noise when operating, and has an outputgas flow of 5 liters per minute or less and has a rechargeable batterycapable of running the concentrator for greater than 2 hours.

In some embodiments, the common member may be disposed at one end of thetwo adsorbers and may include at least one of the input or output ports.In other embodiments an additional common member may be disposed at theother end of the two adsorbers. In some embodiments the additionalcommon member may contain at least one of the input or output ports. Inother embodiments the common member may form a portion of the adsorberseal. In other embodiments the adsorber may contain a flared edge thatforms an additional portion of the adsorber seal. In some embodimentsthe seal may be clamped in place by an additional common member. Inother embodiments the seal may be a face seal between the common memberand the adsorber column. In some embodiments the adsorbers may beconfigured with dimensions to at least one of minimize the width of thetwo attached adsorbers or minimize the length of the two attachedadsorbers. In some embodiments the adsorbers when mated are accessiblefrom the exterior of the platform.

BRIEF DESCRIPTION OF THE DRAWINGS

The understanding of the following detailed description of certainpreferred embodiments of the invention will be facilitated by referringto the accompanying figures.

FIG. 1 shows the general elements of gas concentrators as applicable tocertain embodiments of the invention.

FIG. 2 illustrates the general concept where the concentrator platformis one portion and the user replaceable adsorber is another portion of acomplete concentrator.

FIGS. 3A and 3B illustrate the concentrator sections in both anunassembled and assembled state.

FIGS. 4A and 4B illustrate an assembled concentrator in a case.

FIGS. 5A and 5B depict an exemplary user replaceable adsorber.

FIGS. 6A, 6B, and 6C depict one example of a suitable user actuatableadsorber retention mechanism.

FIGS. 7A, 7B, 7C, and 7D depict another example of a suitable useractuatable adsorber retention mechanism.

FIG. 8 depicts a port seal for a replaceable adsorber where the port isindependently mounted from the platform chassis.

FIGS. 9A, 9B, 9C, and 9D depict another example of a suitable useractuatable adsorber retention mechanism.

FIGS. 10A and 10B depict an alternative port geometry.

FIGS. 11A and 11B depict an arrangement where user replaceable adsorbersare installed with a threaded interface.

FIGS. 12A and 12B depict details of the threaded interface.

FIGS. 13A and 13B depict a twist-lock adsorber interface.

FIGS. 14A, 14B, and 14C depict another example of a suitable useractuatable adsorber retention mechanism.

FIGS. 15A and 15B depict another example of a suitable user actuatableadsorber retention mechanism.

FIGS. 16A and 16B show that alternative inlet and outlet portarrangements are possible.

FIGS. 17A, 17B, 17C and 17D depict a variety of radial sealarrangements.

FIGS. 18A and 18B show an embodiment where one or more of the gasconnections may be directly to a manifold.

FIGS. 19A and 19B show illustrative embodiments of co-attachedadsorbers.

FIGS. 20A and 20B show illustrative alternative embodiments ofco-attached adsorbers.

FIG. 21A shows an illustrative embodiment of co-attached adsorbers witha common member including ports and FIG. 21B shows the embodiment ofFIG. 21a mounted in the platform.

FIGS. 22A and 22B show alternative illustrative embodiments ofco-attached adsorbers with common members including ports.

FIGS. 23A and 23B show additional illustrative embodiments ofco-attached adsorbers.

FIG. 24 shows an illustrative embodiment of face sealing and clampingadsorbers to a common member with ports.

FIG. 25 shows an alternative illustrative embodiment of face sealing andclamping adsorbers to a common member with ports.

FIG. 26 shows another alternative illustrative embodiment of radialsealing and clamping adsorbers to a common member with ports.

FIG. 27 shows an illustrative embodiment of radial sealing and clampinground adsorbers to a common member with ports and an additional elementfor forming the seal.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIG. 1, general features of a portable therapeutic gasconcentrator are shown. Typically gas is drawn into the inlet through aninlet filter 1 into a compressor 2. Compressed air is then delivered ata rate of about 3 LPM to 30 LPM (through various filters and otherdevices) to a gas separation section for selectively adsorbing acomponent of the gas. The preferred embodiments of the invention,although applicable to a variety of gas concentrator implementations,will be described in detail for the case where the inlet gas is air, andthe gas separation section is based on PSA, VSA, VPSA or somecombination thereof, utilizing adsorbent beds 3 which selectively adsorbnitrogen, producing oxygen rich product.

A variety of gas separation section cycle types and bed arrangements areknown in the art, most of which can benefit from the embodiments of theinvention. Whatever the details of the gas separation section 3,typically product gas is accumulated in a storage device 4. Storagedevices may include a tank in the traditional sense, or may be someother device effective for holding a volume of gas, such as a tube, orsome other volume filled with an adsorbent to increase its holdingcapacity or even an empty portion of the adsorber itself at the productend of the adsorber. Many modern concentrators used for therapeuticapplications also include a programmable controller 5 to operate theconcentrator and provide for user interface 8 and communications. Alsotypical are gas exhaust 6, which may have a vacuum applied in the caseof VPSA or VSA systems, and delivery to patient, which often is througha conserver device 7.

Despite the effective moisture mitigative measures described in U.S.Pat. Nos. 7,780,768 and 8,580,015 which might remove 40-98% of watermolecules from the feed gas stream, some moisture will remain in thebeds 3 when the concentrator is turned off. For the case where there isa desiccant layer, even for a very dry design, the desiccant exists toremove any remaining water as well as other impurities, such as CO₂,from the feed gas. During operation impurities are not a significantproblem, as the bed 3 is back-purged or evacuated with vacuumperiodically in the Adsorption Cycle, thereby not leaving time formoisture and other impurities to diffuse into adsorbent. When theconcentrator is not running, particularly for a long period of time,there will be a strong driving force to diffuse for any impuritiesadsorbed on the pretreatment layer (or feed end of the bed in the caseof no pretreatment layer used) or in the gas phase in the void space ofthe desiccant/adsorbent at the feed end of the bed. If the concentratoris not sealed to the outer atmosphere via a valve on the exhaustcontaminants can diffuse either to the outer atmosphere (likewise othercontaminants can diffuse into the beds) or the contaminants can diffuseinto the active “clean” section of the bed(s). If the concentrator issealed to the outer atmosphere via a valve, any impurities present willdiffuse into the bed only. Pretreatment layers are often selected due totheir ease of regeneration during process cycles relative to that forthe contaminants in the active separation layer. Thus during shutdownconditions the result can be a material with a low affinity for a givencontaminant adjacent to a material with a high affinity for a givencontaminant, and a large gradient in chemical potential for thecontaminant provided sufficient treatment of the feed gas has takenplace. Given the complex array of components required to prevent thecontamination of zeolite while a portable oxygen concentrator is runningand while it is in storage, the inventors devised a way to treat thesieve beds as a semi-disposable item so that they can be readilyreplaced rather than protected or overdesigned to achieve the requireddevice service life of the system as a whole.

While it is known in the art to make the zeolite beds easily serviced,there have been no successful designs that minimize the number ofreplacement components and simultaneously retain the ability for thepatient to easily change the sieve In some embodiments, a common membermay be disposed at one end of the two adsorbers and may include at leastone of the input or output ports. In other embodiments an additionalcommon member may be disposed at the other end of the two adsorbers. Insome embodiments the additional common member may contain at least oneof the input or output ports. In other embodiments the common member mayform a portion of the adsorber seal. In other embodiments the adsorbermay contain a flared edge that forms an additional portion of theadsorber seal. In some embodiments the seal may be clamped in place byan additional common member. In other embodiments the seal may be a faceseal between the common member and the adsorber column. In someembodiments the adsorbers may be configured with dimensions to at leastone of minimize the width of the two attached adsorbers or minimize thelength of the two attached adsorbers. In some embodiments the adsorberswhen mated with the platform are accessible from the exterior of theplatform.

The invention herein requires a concentrator to be designed from theground up around the concept of a field replaceable sieve bed. The sievebeds must be easily removed from the system, yet still retain theirair-tight sealing mechanisms and robust resistance to shock, drop, andvibration. In medical oxygen concentrators, and particularly portableoxygen concentrators currently in the marketplace, access to the sievebeds typically requires removal of several outer housing components,tubing connections, fittings, screws, and other hardware components.These designs are simply unsuitable for field service by the user of theoxygen concentrator.

A particularly effective embodiment of the invention is a portableoxygen concentrator where the sieve bed cartridges or adsorbers can beremoved and replaced without removing the outer housing or any fastenersof any kind. FIG. 2 illustrates a preferred embodiment where inlet andoutlet gas connections 201 and 202 are located externally to aconcentrator platform section 20, containing the concentrator elementsother than the adsorber beds, to allow for easy field replacement ofadsorber 21 with inlet and outlet ports 211 and 212 respectively.Further, the adsorbers are robustly attached to core platform 20 towithstand the necessary shock, vibration, and impact a portable oxygenconcentrator may endure via retention mechanism components 203 and 213.By locating the adsorbers 21 outside of the platform 20, the integrityof the concentrator assembly 20 is not compromised by being accessed bythe user who would not have adequate training to perform maintenance oninternal components of the platform 20. The receptacle ports 201 and 202are preferably connected to the air valves by compliant members 9 and10.

A portable concentrator with sieve beds designed for field service issubstantially different than a typical portable oxygen concentrator. Thedesign for patient service changes the layout of the concentrator sothat operational components of the system are accessible to the patientby being located external to the concentrator housing. While this changefacilitates the patient servicing of the system, it also poses aestheticchallenges to the designer since the portable concentrator is usedoutside the home and must not look out of place while being carried by apatient. Therefore, it is an objective of the present invention toseamlessly integrate the adsorbers into the industrial design of theconcentrator so that they remain accessible, but appear to blend in withthe overall design of the concentrator. In a preferred embodiment shownin FIGS. 3A and 3B the adsorbers 21 form the sides of the concentratorwhile the battery 31 forms the bottom of the concentrator. FIGS. 3A and3B further depict a mechanical advantage designed by the inventors touse the mechanically robust battery 31 and battery latching mechanism310 to reinforce the retention of the adsorbers and to preventinadvertent release of the adsorbers during operation. To remove theadsorbers 21 for the purpose of exchanging them, the user would firstremove the battery to access the adsorber release mechanisms 203/213.The entire system 30 is then preferably mounted inside a carrying case40 to enable portable use by the user (FIGS. 4A and 4B).

FIGS. 5A and 5B depict a preferred embodiment of the adsorber designedby the inventors. The adsorber is built as an independent unit and canbe pneumatically interfaced to the platform 20 via inlet and outletports 211 and 212 while being mechanically interfaced to theconcentrator via retention receptacle 214. The internal components ofthe adsorber 21 are similar to other adsorbers found in portable oxygenconcentrators designed by the inventors. The adsorbers contain anitrogen selective adsorbent 219, porous frits 21 d to retain theadsorbent and springs 21 c to prevent the adsorbent from moving andbreaking down during pressure cycling that is typical with a PSA system.The preferred embodiment 21 shows the column cap 21 b being threadedinto the column 21. This embodiment allows the external surfaces of theadsorber to be smooth and free of fasteners or retainers that wouldotherwise pose a hazard to the user while exchanging the adsorbers inthe concentrator. Further, the threaded engagement of the cap to thecolumn ensures that the contaminated adsorbers can be returned to thefactory for replacement of the adsorbent, thus further reducing the costof the adsorber exchange. The cap could alternatively be permanentlyaffixed to the column by rolling the edge of the column over the cap forretention or using adhesive to seal the two parts together, but thesemethods make the adsorber a throw-away item which creates waste. Thepreferred embodiment designed by the inventors allows only the adsorbentor adsorbents to be discarded during an adsorber refurbishment at thefactory.

A further objective of the inventors was to develop an appropriatelatching mechanism that would securely hold the adsorbent vessels sealedto the concentrator, but also allow for easy replacement by the patient.FIGS. 6A, 6B, and 6C depict an exemplary latching mechanism comprised ofa receptacle 214 on the adsorber and a retention plunger 204 on theplatform 20. The latching plunger 204 is held in place by spring forceapplied by spring 204 a. The latch is disengaged by the user by slidingthe engagement button 204 b away from the column latch receptacle 214.The force applied by spring 204 a must be sufficient to preventinadvertent disengagement of the latch, but also low enough to be easilydisengaged by the users' finger without a painful or difficult effort onthe part of the user. The inventors have found that a disengagementforce of approximately 10-25 Newtons meets both of these requirements.As shown in the Figure, the location of the mechanisms could be switchedbetween the adsorber and platform, but it is generally preferable tokeep the cost and complexity as low as possible for the replaceableadsorber, so the latching hardware on the platform is preferable.

FIGS. 7A, 7B, 7C, and 7D depict an alternative embodiment of theinvention where the retainer 216 is engaged by locking tab 215 via therotation of locking screw or knob 206. Reverse rotation of the lockingscrew or knob 206 disengages the locking tab 215 allowing the adsorberto be removed. This design includes the advantage of not requiring aspring to maintain the retention of the adsorber, but the rotationaldesign also may require a common tool such as a Phillips screwdriver orTorx driver to remove or install the adsorbers. Requiring a tool forremoval or installation of the adsorbers might be an advantage in someusage scenarios or a disadvantage in other usage scenarios. Theinventors designed the concentrator system to allow for these differingusage scenarios so that the optimal latching and retention mechanismsmay be chosen accordingly. As for the embodiment of FIGS. 6A, 6B, and6C, the placement of the mechanisms could be reversed as shown, but theplacement of the rotating tab on the platform is preferable.

As in any manufacturing operation, there will be variations in thedimensions of all components of the system, so the user replaceableadsorbent must contain a significant amount of sealing overlap toprevent inadvertent leakage that would degrade the system's performance.Referring to FIG. 8, in a particular embodiment, the inlet and outletconnections 211 and 212 must therefore contain overlapping sealingelements that allow for some positional compliance without sacrificingthe quality of the sealing of the pneumatic connections. This compliantsealing mechanism is achieved by using an o-ring on the adsorber and avertical bore 201 a on the receptacle 201 that creates a seal along itsentire length, thus allowing between 1 and 5 millimeters of verticalcompliance to the seal. This compliance allows for some variation andcompliance in the latch as well as some variation in the height of thecolumn components that would be seen in a typical manufacturedcomponent. Further, FIG. 8 depicts the gas receptacle 201 as a modularcomponent that is independent of the platform 20. This is accomplishedby connecting adsorber receptacle port 201 directly to compliant member9, with a locking mechanism 201 b. Thus platform 20 is used to locatethe port 201, but they are not a shared structure. By decoupling thepneumatics from the structural elements of the system, the pneumaticsare protected from the adverse affects of drop or impact. In the extremecase when platform 20 housing components are broken during impact ordrop, port 201 may likely stay connected to member 9 and column inlet oroutlet fitting 212 a. Thus the pneumatic system integrity may bemaintained by adhering to the modular gas connector system 201 and 212as shown in FIG. 8 even in the event of damage to the core system 20.

FIGS. 9A, 9B, 9C, and 9D depict an alternate latching mechanism thatutilizes push button adsorber release buttons 207 to disengage thelatching mechanism 207 b and 207 c and release the adsorbers 21. Again,the spring 207 a must exert an optimal force of about 10 to 25 Newtonson the latching mechanism to sufficiently secure the adsorber 21 duringuse and pressure cycling while still enabling the finger of the user toovercome the spring force and release the adsorber 21 without discomfortor difficulty.

FIGS. 10A and 10B depict another alternate embodiment of the inventionwhere the axis of insertion of the inlet and outlet ports 211 and 212are perpendicular to the axis of flow of gas through the adsorber 21.This embodiment simplifies the design by utilizing the same gasconnections at the inlet and the outlet port, but does not have theadvantage of being able to utilize the battery as a redundant retentionmechanism during use.

The coaxial threaded adsorbers 21 in FIGS. 11A, 11B, 12A and 12B areanother embodiment of the invention where both gas inlet and gas outletports 211 and 212 are coaxial and located at the same end of theadsorber by utilizing an integral return tube to retrieve gas from theopposite end of the column. The engagement and retention threads 217create the mechanically robust connection between adsorber 21 andplatform 20 while the pneumatic connections 211 and 212 are radiallysealed by o-rings with sufficient vertical overlap to allow adsorber 21to seal in any rotational orientation such that rotational position ortiming is independent from the sealing. Adsorber endcap 21 a is threadedonto return tube connection 212 to seal the return tube. Adsorber endcapis then sealed to column 21 c in any rotation by any number of possiblesealing methods such as an o-ring or face seal gasket. The entireadsorber including column 21 c and endcap 21 a then mate to core section20 to form a complete portable oxygen concentrator. The rotationalindependence ensures that user replacement of the adsorber and thevariable tightening torque applied by the user will not createdetrimental leaks at the inlet and outlet gas connections.

The alternate embodiment of the invention depicted in FIGS. 13A and 13Butilize a twist-lock mechanism to lock the adsorber 21 to the platform20. Progressively engaging locking tab 218 draws adsorber 21 into thereceptacle located in platform 20 and is ideally employed in combinationwith the coaxial adsorber design where both inlet and outlet ports 211and 212 are collocated at a single end of the adsorber. Alternatively,one of the inlet or outlet ports may be located at the opposing end ofthe adsorber 21 and the gas connection may be made with a flexibletubing element 10 as depicted in FIGS. 15A and 15B.

Yet another alternate embodiment of the user replaceable adsorber isdepicted in FIGS. 14A and 14B. In this embodiment, adsorber 21 is heldin place to platform 20 by a hinged floorplate 209 such that noretention elements at all are required on the adsorber 21. In thisembodiment the hinge 209 a and the latch 209 b are both mounted on theplatform 20 such that floorplate prevents the adsorber from disengagingfrom the platform 20 when latched in the closed position by latch 209 b.

The specific definition of the inlet and outlet ports on adsorber 21 aremerely chosen by convention and can be reversed in any embodiment asdepicted in FIGS. 16A and 16B. A typical adsorber as designed by theinventors utilizes a larger inlet port where feed gas enters the columnto prevent power losses caused by flow restriction and a smaller port onthe product end or outlet where the oxygen exits the adsorber or entersthe adsorber during the purge step of the PSA cycle. In constructing theadsorber, the feed or inlet end of the adsorber may be further definedwhen a layered adsorbent system is utilized and a pretreatment layer isused to remove contaminants from the feed stream prior to the exposingthe main layer adsorbent to the feed stream.

Inlet and outlet ports and receptacles 201 and 211 may utilize a varietyof well established sealing elements as depicted in FIGS. 17A, 17B, 17C,and 17D. Sealing element 17 is ideally a compliant o-ring made from oneof several compounds such as rubber, viton, or silicone. Alternately,the sealing element 17 may be a custom face sealing gasket also made ofrubber, viton, or silicone, but this embodiment may lack the necessarycompliance to produce a repeatable and robust seal as part tolerancesvary in a high volume production environment.

Although the preferred approach to connect the adsorber/receptacle portsto the platform internal valving is by compliant member for increasedresistance to shock, it is certainly possible to make one or more theseconnections by having the receptacle ports connect directly to amanifold. Such an arrangement is shown by way of example where one portof adsorber 21 connects directly to manifold 181 as shown in FIGS. 18Aand 18B.

It may be convenient in some embodiments, to mount the adsorbers next toeach other in platform 20, and to attach the adsorbers together, so thatthe placement of both adsorbers is facilitated to be easily performed inone operation and to potentially minimize part count by utilizing partsthat serve as common structural and pneumatic components. Severalversions of two adsorbers attached and mounted adjacent to each otherare possible within the teachings of this disclosure.

FIGS. 19A and 19B show adsorbers 21 held together with one common member191, which both attaches the adsorbers together and holds them with allports 211 and 212 aligned for mounting. FIG. 19A shows the ports 211 and212 on each end of adsorbers 21 in the configuration where the inlet andoutlet flow is substantially along the same axis as the flow axis of theadsorbers. This configuration is a co-mounted version of the arrangementshown in FIGS. 5A and 5B, with different mounting embodiments shown inFIGS. 6 to 9. FIG. 19B shows the ports 211 and 212 on each end ofadsorbers 21 in the configuration where the inlet and outlet flow issubstantially perpendicular to the flow axis of the adsorbers. This is aco-mounted version of the configuration shown in FIGS. 10A and 10B. Toshow the various possibilities for co-mounted adsorbers FIG. 19A showscurved rectangular adsorbers while FIG. 19B shows round adsorbers suchas are shown in the earlier Figures. Other shapes, such trapezoids,ovals, D-shaped, and combinations thereof, as are possible and fallwithin the claimed scope of this application. The appropriate shape foran adsorber may be determined by the design of the platform 20 as wellas the size, wall thickness, and operating pressure of the adsorber toensure structural integrity.

FIGS. 20A and 20B show adsorbers 21 held together with two commonmembers 191 and 192, which both attach the adsorbers together and holdsthem with all ports 211 and 212 aligned for mounting. FIG. 20A shows theports 211 and 212 on each end of adsorbers 21 in the configuration wherethe inlet and outlet flow is substantially perpendicular to the flowaxis of the adsorbers. This is a co-mounted version of the configurationshown in FIGS. 10A and 10B. FIG. 20B shows the ports 211 and 212 on eachend of adsorbers 21 in the configuration where the inlet and outlet flowis substantially along the same flow axis of the adsorbers. Thisconfiguration is a co-mounted version of the arrangement shown in FIGS.5A and 5B, with different mounting embodiments shown in FIGS. 6 to 9.Again both round and rectangular adsorbers are shown by way of example.

FIG. 21A shows adsorbers 21 held together with one common member 191,which both attaches the adsorbers together and holds them with all ports211 and 212 aligned for mounting. FIG. 21A shows the ports 211 and 212on each end of adsorbers 21 in the configuration where the inlet andoutlet flow is substantially along the same axis as the flow axis of theadsorbers. Common member 191 also includes the ports 212. Ports 212 areformed into common member 191 and sealed to the adsorbers 21 in avariety of ways, some of which will be shown below. FIG. 21B shows theembodiment of FIG. 21A mounted into platform 20 where the rectangularshape of the adsorbers 21 are used to minimize the width of the platform20 compared to a round adsorber. The rectangular length to width ratioof the adsorber is approximately 1.5 to 1 to allow the completedconcentrator to be narrower than two circular adsorbers of equivalentcross section would allow. The rectangular shape with flat sidesrequires precise design to prevent undue flexing or rupture caused bythe constant pressure cycling of a pressure swing adsorption system. Thecolumns are fixed into place by retention mechanism 207. Variousretention mechanisms are described above, and these retention mechanismsmay for most cases be applied to two adorber columns held together.

FIG. 22A shows adsorbers 21 held together with one common member 191which includes ports 212, which both attaches the adsorbers together andholds them with all ports 211 and 212 aligned for mounting. FIG. 22Ashows the ports 211 and 212 on each end of adsorbers 21 in theconfiguration where the inlet and outlet flow is substantially along thesame axis as the flow axis of the adsorbers. FIG. 22A additionallycontains an additional common member 192 that hold the adsorberstogether without integrating with the adsorber seals or ports. FIG. 22Bshows an additional common member 192 at the other end of adsorbers 21,and in this embodiment, additional common member 192 includes ports 211and additionally participates in the adsorber sealing depicted in FIGS.24-27.

FIG. 23A shows adsorbers 21 held together with one common member 191which includes ports 212, which both attaches the adsorbers together,seals the adsorbers as shown in FIGS. 24-27, and holds them with allports 211 and 212 aligned for mounting. FIG. 19A shows the ports 211 and212 on each end of adsorbers 21 in the configuration where the inlet andoutlet flow is substantially perpendicular to the flow axis of theadsorbers. FIG. 23A also shows an additional common member near theother end of adsorbers 21. FIG. 23B shows an additional common member192 at the other end of adsorbers 21, and in this embodiment, additionalcommon member 192 includes ports 211 and adsorber seals from FIGS.24-27. Both FIGS. 23A and 23B show the shape of the adsorbers modifiedto achieve a specific form factor for the completed concentrator. In theembodiment shown, the width of the adsorbers is minimized to allow for adifferent packing optimization compared to the embodiment in FIG. 21 or22 or circular adsorbers of similar cross sectional area.

FIG. 24 shows an illustrative embodiment for sealing adsorbers 21 tocommon member 191 when common member 191 includes ports 212. This andother sealing embodiments will work just as well on the other end of theadsorbers for ports 211 and for either the parallel or perpendicularport flow configurations. In the embodiment of FIG. 24 seal 241 residesbetween common member 191 and clamp portion 242 of the common member.Clamp 242 pushes the bottom end of adsorbers 21 onto seal 241. Clamp 242may be pressed on or attached with fasteners. Any arrangement of clamp242 that applies an appropriate force down on seal 241 will suffice.Seal 241 in the embodiment shown is a face seal.

FIG. 25 shows another illustrative embodiment for sealing adsorbers 21to common member 191 when common member 191 includes ports 212. In theembodiment of FIG. 25 seal 241 resides between common member 191 andclamp portion 242 of the common member. Both clamp portion 242 and thebottom end of the adsorbers 21 have a flared edge 243. Clamp 242 pushesthe bottom end of adsorbers 21 onto seal 241. Flared edges 243 provideenhanced inward and downward force when the clamp 242 is tightened intoplace. Again seal 241 in the embodiment shown is a face seal.

FIG. 26 shows another illustrative embodiment for sealing adsorbers 21to common member 191 when common member 191 includes ports 212. In theembodiment of FIG. 26 0-ring seal 241 resides between common member 191and the inside wall of adsorber wall 21. Clamp 242 retains common member191 to adsorbers 21 while the o-ring seals the adsorber column

FIG. 27 shows another illustrative embodiment for sealing adsorbers 21to common member 191 when common member 191 includes ports 212. In theembodiment of FIG. 27 Each column is individually clamped and sealed tocommon member 191. Seal 241, an o-ring seal in the embodiment shown,resides between common member 191 and the inner wall of adsorber 21.Common member 191 includes an additional element 245 for forming theseal retaining groove for o-ring seal 241. Clamp 242 pushes the innerwall of adsorbers 21 radially against seal 241.

The foregoing description of the preferred embodiments of the presentinvention has shown, described and pointed out the fundamental novelfeatures of the invention. It will be understood that various omissions,substitutions, and changes in the form of the detail of the apparatus asillustrated as well as the uses thereof, may be made by those skilled inthe art, without departing from the spirit of the invention.Consequently, the scope of the invention should not be limited to theforegoing discussions, but should be defined by appended claims.

What is claimed is:
 1. A portable oxygen concentrator, comprising: aplatform, comprising: a housing, a controller, a user interface, atleast one compressor, at least one air control valve, and at least oneadsorber receptacle comprising at least one gas connector port; at leasttwo adsorbers configured to be user replaceable, each of the at leasttwo adsorbers comprising: a column having a top end and a bottom end,the column configured to contain a nitrogen selective adsorbentmaterial, wherein a flow axis of gas through the column is between thetop and bottom ends, a first disconnectable pressure sealed gasconnector and a second disconnectable pressure sealed gas connector,each of the first disconnectable pressure sealed gas connector and thesecond disconnectable pressure sealed gas connector comprising a centralaxis, wherein the first disconnectable pressure sealed gas connector andthe second disconnectable pressure sealed gas connector are in fluidcommunication with the nitrogen selective adsorbent material and extendparallel to the flow axis in the same direction and the central axes ofthe first disconnectable pressure sealed gas connector and the seconddisconnectable pressure sealed gas connector are parallel to each other;wherein the at least two adsorbers are configured to mate with theplatform; and wherein the at least two adsorbers are attached together;and a retention mechanism accessible on the exterior of the platform;wherein the retention mechanism removably secures the at least twoadsorbers to the platform; wherein the retention mechanism is at leastone of tool or hand operable; and wherein the portable oxygenconcentrator weighs less than 10 pounds, and has an output gas flow of 5liters per minute or less and has a rechargeable battery capable ofrunning the portable oxygen concentrator for greater than 2 hours. 2.The portable oxygen concentrator of claim 1, wherein the retentionmechanism comprises a rotatable tab.
 3. The portable oxygen concentratorof claim 2, wherein the rotatable tab is rotatable into a slot toremovably secure the at least two adsorbers to the platform.
 4. Theportable oxygen concentration of claim 2, wherein the retentionmechanism comprises a screw or knob coupled to the rotatable tab.
 5. Theportable oxygen concentrator of claim 1, wherein the portable oxygenconcentrator weighs less than 8 pounds.
 6. The portable oxygenconcentrator of claim 1, wherein the rechargeable battery is removablysecured to the platform.
 7. The portable oxygen concentrator of claim 1,wherein the at least one gas connector port comprises an inlet port andan outlet port for each of the at least two adsorbers, wherein the inletports and the outlet ports each contain at least one radial seal.
 8. Theportable oxygen concentrator of claim 1, wherein the firstdisconnectable pressure sealed gas connector and the seconddisconnectable pressure sealed gas connector are each sealed by acompliant sealing mechanism.
 9. The portable oxygen concentrator ofclaim 8, wherein the compliant sealing mechanism comprises an o-ring.10. The portable oxygen concentrator of claim 1, wherein the at leasttwo adsorbers are joined by at least one common member.
 11. The portableoxygen concentrator of claim 10, wherein the at least one common memberis disposed at one end of the at least two adsorbers.
 12. The portableoxygen concentrator of claim 10, wherein the at least one common memberforms a portion of an adsorber seal.
 13. The portable oxygenconcentrator of claim 10, wherein at least two adsorbers comprises afirst adsorber and a second adsorber, and wherein the at least onecommon member holds the first adsorber relative the second adsorber suchthat the first disconnectable pressure sealed gas connector and thesecond disconnectable pressure sealed gas connector of the firstadsorber align with the first disconnectable pressure sealed gasconnector and the second disconnectable pressure sealed gas connector ofthe second adsorber.
 14. The portable oxygen concentrator of claim 1,further comprising at least one air filter.
 15. The portable oxygenconcentrator of claim 1, wherein the portable oxygen concentratorproduces less than 45 decibels acoustic noise while operating.
 16. Theportable oxygen concentrator of claim 1, wherein a total volume of theportable oxygen concentrator is less than 600 cubic inches.
 17. Theportable oxygen concentrator of claim 1, wherein the at least twoadsorbers are configured to be user replaceable without removal of anyfasteners.
 18. The portable oxygen concentrator of claim 1, wherein eachof the at least two adsorbers is round in shape.
 19. The portable oxygenconcentrator of claim 1, further comprising a case configured to enclosethe platform, the at least two adsorbers, and the battery when theplatform, the at least two adsorbers, and the battery are matedtogether.
 20. The portable oxygen concentrator of claim 1, wherein theportable oxygen concentrator is configured to provide a product gasstream comprising an oxygen concentration between 80% and 95% purity.